1. Field of the Invention
This invention relates to a scanning photoelectron microscope, and particularly to a scanning photoelectron microscope for observing therethrough a sample having much gas emission, a sample containing water, etc.
2. Related Background Art
In recent years, attention has been paid to a scanning photoelectron microscope as an apparatus for observing therethrough the chemically coupled state of the surface of a sample.
The scanning photoelectron microscope has scanned a sample placed in a vacuum state higher than 10.sup.-1 Pa with an energy beam (such as X-rays or ultraviolet rays), has processed photoelectrons created from the sample by this scanning in the following manner and has displayed the result on a CRT.
That is, the photoelectrons created from the sample have been detected by a detector comprising a combination of a microchannel plate or a scintillator and a photoelectronic multiplier tube.
The photoelectrons detected by the detector have been stored as an image signal in an image memory in synchronism with the aforementioned scanning, and have been displayed on the CRT.
Also, when it is desired to observe photoelectrons having desired energy, an electron energy analyzer has been disposed between the sample and the detector, and only the photoelectrons having desired energy have been taken out by this electron energy analyzer, whereafter the photoelectrons having desired energy have been detected by the detector.
By the prior-art detector, however, the photoelectrons created from the sample can be detected only in the aforementioned high vacuum state, and this has led to a problem that a sample having much gas emission and a sample containing water cannot be observed.